Power amplifier module

ABSTRACT

A power amplifier module includes a first amplifier circuit that amplifies a radio frequency signal with a first gain corresponding to a first control signal to generate a first amplified signal; a second amplifier circuit that amplifies the first amplified signal with a second gain corresponding to a second control signal to generate a second amplified signal; and a control unit that generates the first control signal and the second control signal. The second control signal is a control signal for increasing a power-supply voltage for the second amplifier circuit as a peak-to-average power ratio of the radio frequency signal increases. The first control signal is a control signal for controlling the first gain of the first amplifier circuit so that a variation in the second gain involved in a variation in the power-supply voltage for the second amplifier circuit is compensated for.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Continuation of U.S. patent application Ser. No. 16/190,861filed on Nov. 14, 2018, which claims priority from Japanese PatentApplication No. 2017-221424 filed on Nov. 17, 2017. The contents ofthese applications are incorporated herein by reference in theirentireties.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The present disclosure relates to a power amplifier module.

Description of the Related Art

In recent years, in wireless communication systems, techniques such asmulti-level modulation and multi-carrier transmission are used, therebyincreasing transmission capacity. In multi-level modulation,multi-carrier transmission, and so forth, a plurality of signalwaveforms are combined, thereby increasing a peak-to-average power ratio(PAPR). In a power amplifier that amplifies a signal with such a highPAPR, a backoff operation is typically performed in which amplificationis performed with an output being lower than a maximum output to achievelinearity. On the other hand, in the case where a signal with a low PAPRis amplified, linearity is maintained even when the backoff of the poweramplifier is small, thus enabling the power amplifier to operate in amode in which efficiency is emphasized.

For example, Japanese Unexamined Patent Application Publication No.2009-81692 discloses a wireless communication apparatus including twoamplification paths with different power consumption configured toamplify a modulated signal; and a control unit configured to performcontrol so that an amplification path selected in accordance with thenumber of subcarriers included in the modulated signal amplifies themodulated signal. With respect to a signal with a large number ofsubcarriers, that is, a signal with a high PAPR, the wirelesscommunication apparatus performs amplification using an amplificationpath having low efficiency and a large backoff. With respect to a signalwith a small number of subcarriers, that is, a signal with a low PAPR,the wireless communication apparatus performs amplification using anamplification path having high efficiency and a small backoff.

However, in a configuration in which a plurality of amplification pathsare switched, gain differs according to an amplification path, thuscausing variations in gain. Furthermore, a plurality of amplificationpaths are necessary, thereby making it impossible to reduce the size ofa module. Additionally, switching loss due to switching betweenamplification paths occurs.

BRIEF SUMMARY OF THE DISCLOSURE

The present disclosure has been made in consideration of suchcircumstances to provide a power amplifier module that enablesimprovements in linearity and efficiency with a simple configuration.

A power amplifier module according to one preferred embodiment of thepresent disclosure includes a first amplifier circuit configured toamplify a radio frequency signal with a first gain corresponding to afirst control signal to generate a first amplified signal; a secondamplifier circuit configured to amplify the first amplified signal witha second gain corresponding to a second control signal to generate asecond amplified signal; and a control unit configured to generate thefirst control signal and the second control signal. The second controlsignal is a control signal for increasing a power-supply voltage for thesecond amplifier circuit as a peak-to-average power ratio of the radiofrequency signal increases. The first control signal is a control signalfor controlling the first gain of the first amplifier circuit so that avariation in the second gain involved in a variation in the power-supplyvoltage for the second amplifier circuit is compensated for.

Preferred embodiments of the present disclosure may provide a poweramplifier module that enables improvements in linearity and efficiencywith a simple configuration.

Other features, elements, characteristics and advantages of the presentdisclosure will become more apparent from the following detaileddescription of preferred embodiments of the present disclosure withreference to the attached drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a circuit diagram of a radio frequency (RF) signal processingmodule according to a first embodiment of the present disclosure;

FIG. 2 illustrates changes in gain and linearity of a power-stageamplifier as a function of a change in power-supply voltage;

FIG. 3 is a circuit diagram of an RF signal processing module accordingto a second embodiment of the present disclosure;

FIG. 4A is a circuit diagram of a low pass filter circuit havingvariable impedence;

FIG. 4B is a circuit diagram of a high pass filter circuit havingvariable impedence;

FIG. 5A illustrates changes in gain and linearity of the power-stageamplifier as a function of a change in impedance of a matching network;and

FIG. 5B illustrates changes in gain and linearity of the power-stageamplifier as a function of a change in impedance of the matchingnetwork.

DETAILED DESCRIPTION OF THE DISCLOSURE

Preferred embodiments of the present disclosure will be described withreference to the accompanying drawings. In figures, elements denoted bythe same reference numerals have the same or similar configuration.

First Embodiment (1) Configuration of RF Signal Processing Module 100

FIG. 1 is a circuit diagram of a radio frequency (RF) signal processingmodule 100 according to a first embodiment of the present disclosure.The RF signal processing module 100 includes a radio frequencyintegrated circuit (RFIC) 1, a power amplifier module 2, a control unit3 (e.g., a control circuit such as a controller, microprocessor,integrated circuit, or the like), a power supply circuit 4, and a powersupply circuit 5.

(1-1) RFIC 1

The RFIC 1 is a radio frequency integrated circuit, and modulates asignal supplied from a baseband processing unit or the like, which isnot illustrated, into a high-frequency signal to generate a radiofrequency (RF) signal. The frequency of an RF signal ranges from aboutseveral hundred MHz to several GHz, for example.

(1-2) Power Amplifier Module 2

The power amplifier module 2 is a circuit that amplifies an RF signalgenerated by the RFIC 1. As illustrated in FIG. 1, the power amplifiermodule 2 includes a drive-stage amplifier circuit 2D (the firstamplifier circuit) constituting a first-stage amplifier circuit, and apower-stage amplifier circuit 2P (the second amplifier circuit)constituting a subsequent-stage amplifier circuit.

(1-2-1) Drive-Stage Amplifier Circuit 2D

As illustrated in FIG. 1, the drive-stage amplifier circuit 2D includes,for example, a drive-stage amplifier 10D, a variable attenuator 30, amatching network 20A, and a matching network 20B.

The drive-stage amplifier 10D receives a power-supply voltage Vccdsupplied by the power supply circuit 4 and amplifies the RF signalinputted from the RFIC 1 through the variable attenuator 30, thematching network 20A, and so forth to generate a first amplified signal.The drive-stage amplifier 10D may be, for example, a bipolar transistorsuch as a heterojunction bipolar transistor (HBT), or may be afield-effect transistor such as a metal-oxide-semiconductor field-effecttransistor (MOSFET). The drive-stage amplifier 10D may be constituted bya plurality of power amplifiers. The power-supply voltage Vccd suppliedby the power supply circuit 4 to the drive-stage amplifier 10D variesaccording to a control signal Sd from the control unit 3 which isdescribed below.

The variable attenuator 30 is provided between the RFIC 1 and thematching network 20A. The variable attenuator 30 includes, for example,a plurality of attenuators and a plurality of line switches, andattenuates the power of an input signal. A power attenuation factorcorresponding to the power ratio between an input signal and an outputsignal of the variable attenuator 30 varies according to a controlsignal Sr from the control unit 3 which is described below.

The matching network 20A is provided between the variable attenuator 30and the drive-stage amplifier 10D and matches the impedance of thevariable attenuator 30 to that of the drive-stage amplifier 10D. Thematching network 20A is constituted by, for example, a low pass or highpass filter circuit having variable impedence. The impedance of thematching network 20A varies according to a control signal Sa from thecontrol unit 3 which is described below. Here, the RF signal processingmodule 100 may have a configuration in which the variable attenuator 30and the matching network 20A are interchanged.

The matching network 20B is provided between the drive-stage amplifier10D and a power-stage amplifier 10P and matches the impedance of thedrive-stage amplifier 10D to that of the power-stage amplifier 10P. Thematching network 20B is constituted by, for example, a low pass, highpass, or combination low pass-high pass filter circuit having variableimpedence. The impedance of the matching network 20B varies according toa control signal Sb from the control unit 3 which is described below.

The gain (the first gain) of the drive-stage amplifier circuit 2D variesaccording to the power supply circuit 4 or a component of thedrive-stage amplifier circuit 2D. That is, as the power-supply voltageVccd supplied by the power supply circuit 4 increases, the gain of thedrive-stage amplifier 10D increases, and the gain of the drive-stageamplifier circuit 2D therefore increases. As the power attenuationfactor of the variable attenuator 30 increases, the magnitude of aninput signal to the drive-stage amplifier 10D decreases, and the gain ofthe drive-stage amplifier circuit 2D therefore decreases. As theimpedance of the matching network 20A increases, the magnitude of areflected wave at an input end of the matching network 20A increases,and the gain of the drive-stage amplifier circuit 2D thereforedecreases. Furthermore, as the impedance of the matching network 20Bincreases, the gain of the drive-stage amplifier 10D increases, and thegain of the drive-stage amplifier circuit 2D therefore increases.

(1-2-2) Power-Stage Amplifier Circuit 2P

As illustrated in FIG. 1, the power-stage amplifier circuit 2P includes,for example, the power-stage amplifier 10P, and a matching network 20C.

The power-stage amplifier 10P receives a power-supply voltage Vccpsupplied by the power supply circuit 5 and amplifies the first amplifiedsignal inputted from the drive-stage amplifier 10D through the matchingnetwork 20B and so forth to generate a second amplified signal. Thepower-stage amplifier 10P may be, for example, a bipolar transistor suchas an HBT, or may be a field-effect transistor such as a MOSFET. Thepower-supply voltage Vccp supplied by the power supply circuit 5 to thepower-stage amplifier 10P varies according to a second control signal S2from the control unit 3 which is described below.

Here, changes in gain and linearity of the power-stage amplifier 10P asa function of a change in the power-supply voltage Vccp will bedescribed with reference to FIG. 2. FIG. 2 illustrates relationshipsbetween the output and gain of the power-stage amplifier 10P withrespect to a plurality of values of the power-supply voltage Vccp. Thatis, reference numerals 501, 502, 503, 504, 505, 506, and 507respectively represent graphs representing relationships between theoutput and gain of the power-stage amplifier 10P at power-supplyvoltages Vccp of about 2.0 V, about 2.5 V, about 3.0 V, about 3.5 V,about 4.0 V, about 4.5 V, and about 5.0 V. Furthermore, referencenumerals 601, 602, 603, 604, 605, 606, and 607 respectively represent P1dB values of the power-stage amplifier 10P at power-supply voltages Vccpof about 2.0 V, about 2.5 V, about 3.0 V, about 3.5 V, about 4.0 V,about 4.5 V, and about 5.0 V. Here, P1 dB refers to an output at a pointat which the gain decreases by 1 dB with respect to an ideal linearcharacteristic. As illustrated in FIG. 2, it may be said that, as thepower-supply voltage Vccp increases, the gain of the power-stageamplifier 10P increases. Furthermore, as illustrated in FIG. 2, it maybe said that, as the power-supply voltage Vccp increases, the P1 dB ofthe power-stage amplifier 10P increases, and the linearity improves.

The gain (the second gain) of the power-stage amplifier circuit 2Pvaries according to the power supply circuit 5. That is, as thepower-supply voltage Vccp supplied by the power supply circuit 5increases, the gain of the power-stage amplifier 10P increases, and thegain of the power-stage amplifier circuit 2P therefore increases, too.

The matching network 20C is provided between the power-stage amplifier10P and an antenna 6 and matches the impedance of the power-stageamplifier 10P to that of the antenna 6. The matching network 20C(impedance matching network) is constituted by, for example, a low passor high pass filter circuit, or a combination low pass-high pass filtercircuit.

(1-3) Control Unit 3

The control unit 3 is connected to the RFIC 1 and the power amplifiermodule 2. The control unit 3 detects a predetermined signal generated bythe RFIC 1 and generates a first control signal S1 for controlling thedrive-stage amplifier circuit 2D, and the second control signal S2 forcontrolling the power-stage amplifier circuit 2P.

The first control signal S1 is a control signal for controlling the gainof the drive-stage amplifier circuit 2D so that a variation in the gainof the power-stage amplifier circuit 2P involved in a variation in thepower-supply voltage Vccp supplied by the power supply circuit 5 iscompensated for. The first control signal S1 includes, for example, atleast any of the control signal Sr for controlling the variableattenuator 30, the control signal Sa for controlling the matchingnetwork 20A, the control signal Sd for controlling the power supplycircuit 4, and the control signal Sb for controlling the matchingnetwork 20B.

The second control signal S2 is a control signal for increasing thepower-supply voltage Vccp for the power-stage amplifier circuit 2P as apeak-to-average power ratio (PAPR) of the RF signal generated by theRFIC 1 increases. The second control signal S2 is a control signal forcontrolling the power supply circuit 5.

(2) Operation of RF Signal Processing Module 100

Next, the operation of the RF signal processing module 100 will bedescribed.

(2-1) Operation of Power-Stage Amplifier Circuit 2P

The control unit 3 detects a signal having information about a PAPR ofan RF signal generated by the RFIC 1, calculates the PAPR of the RFsignal, and then generates the second control signal S2 for increasingthe power-supply voltage Vccp for the power-stage amplifier 10P suppliedby the power supply circuit 5 as the calculated PAPR increases. Asdescribed above with reference to FIG. 2, as the power-supply voltageVccp increases, the P1 dB of the power-stage amplifier 10P increases(the linearity improves), and the gain of the power-stage amplifiercircuit 2P also increases. Hence, as the PAPR of the RF signal generatedby the RFIC 1 increases, the P1 dB of the power-stage amplifier 10Pincreases (the linearity improves), and the gain of the power-stageamplifier circuit 2P also increases.

(2-2) Operation of Drive-Stage Amplifier Circuit 2D

The control unit 3 generates the first control signal S1 for controllingthe gain of the drive-stage amplifier circuit 2D so that a variation inthe gain of the power-stage amplifier circuit 2P involved in a variationin the power-supply voltage Vccp supplied by the power supply circuit 5is compensated for.

Specifically, for example, when the gain of the power-stage amplifiercircuit 2P increases, the control unit 3 controls a line switch of thevariable attenuator 30 by using the control signal Sr to increase thepower attenuation factor of the variable attenuator 30, thereby reducingthe gain of the drive-stage amplifier circuit 2D. For example, when thegain of the power-stage amplifier circuit 2P increases, the control unit3 increases the impedance of the matching network 20A by using thecontrol signal Sa to increase the magnitude of a reflected wave at theinput end of the matching network 20A, thereby reducing the gain of thedrive-stage amplifier circuit 2D. For example, when the gain of thepower-stage amplifier circuit 2P increases, the control unit 3 reducesthe power-supply voltage Vccd supplied by the power supply circuit 4 byusing the control signal Sd, thereby reducing the gain of thedrive-stage amplifier circuit 2D. Furthermore, for example, when thegain of the power-stage amplifier circuit 2P increases, the control unit3 reduces the impedance of the matching network 20B by using the controlsignal Sb, thereby reducing the gain of the drive-stage amplifiercircuit 2D.

Similarly, when the gain of the power-stage amplifier circuit 2Pdecreases, the control unit 3 controls a line switch of the variableattenuator 30 by using the control signal Sr to reduce the powerattenuation factor of the variable attenuator 30, thereby increasing thegain of the drive-stage amplifier circuit 2D. For example, when the gainof the power-stage amplifier circuit 2P decreases, the control unit 3reduces the impedance of the matching network 20A by using the controlsignal Sa to reduce the magnitude of a reflected wave at the input endof the matching network 20A, thereby increasing the gain of thedrive-stage amplifier circuit 2D. For example, when the gain of thepower-stage amplifier circuit 2P decreases, the control unit 3 increasesthe power-supply voltage Vccd supplied by the power supply circuit 4 byusing the control signal Sd, thereby increasing the gain of thedrive-stage amplifier circuit 2D. Furthermore, for example, when thegain of the power-stage amplifier circuit 2P decreases, the control unit3 increases the impedance of the matching network 20B by using thecontrol signal Sb, thereby increasing the gain of the drive-stageamplifier circuit 2D.

Second Embodiment

FIG. 3 is a circuit diagram of an RF signal processing module 200according to a second embodiment of the present disclosure. Hereinafter,among elements of the RF signal processing module 200, elements thatdiffer from those of the RF signal processing module 100 according tothe first embodiment of the present disclosure will be described, andthe description of elements that are the same as those of the RF signalprocessing module 100 is appropriately omitted.

(1) Configuration of RF Signal Processing Module 200

As described below, the impedance of the matching network 20C includedin the RF signal processing module 200 is variable. The control unit 3included in the RF signal processing module 200 generates, as the secondcontrol signal S2, a control signal for controlling the matching network20C.

The matching network 20C included in the RF signal processing module 200is, for example, a low pass filter circuit having variable impedence asillustrated in FIG. 4A. Specifically, the matching network 20C includes,for example, an inductor L1 connected in series between the power-stageamplifier 10P and the antenna 6, and a variable capacitance element C1and a resistance element R1 that are connected in shunt between thepower-stage amplifier 10P and the antenna 6. The variable capacitanceelement C1 is constituted by, for example, a plurality of capacitanceelements and a plurality of line switches. Each line switch is switchedbetween ON and OFF states in accordance with the second control signalS2, and a capacitance value of the variable capacitance element C1 thuschanges. Furthermore, the inductor L1 may be configured to have avariable inductance value.

Furthermore, the matching network 20C included in the RF signalprocessing module 200 is, for example, a high pass filter circuit havingvariable impedence as illustrated in FIG. 4B. Specifically, the matchingnetwork 20C includes, for example, a capacitance element C2 connected inseries between the power-stage amplifier 10P and the antenna 6, and avariable inductor L2 and a resistance element R2 that are connected inshunt between the power-stage amplifier 10P and the antenna 6. Thevariable inductor L2 is constituted by, for example, a plurality ofinductors and a plurality of line switches. Each line switch is switchedbetween ON and OFF states in accordance with the second control signalS2, and an inductance value of the variable inductor L2 thus changes.Furthermore, the capacitance element C2 may be configured to have avariable capacitance value.

Here, changes in gain and linearity of the power-stage amplifier 10P asa function of a change in impedance of the matching network 20C will bedescribed with reference to FIGS. 5A and 5B. FIG. 5A illustrates arelationship between the output and gain of the power-stage amplifier10P obtained when the impedance of the matching network 20C is about 3Ω.FIG. 5B illustrates a relationship between the output and gain of thepower-stage amplifier 10P obtained when the impedance of the matchingnetwork 20C is about 8Ω. As illustrated in FIGS. 5A and 5B, it may besaid that, as the impedance of the matching network 20C decreases, thegain of the power-stage amplifier 10P decreases. Furthermore, in a graphillustrated in FIG. 5A, P1 dB is about 29 dBm. In a graph illustrated inFIG. 5B, P1 dB is about 24.5 dBm. Hence, in the case illustrated inFIGS. 5A and 5B, it may be said that, as the impedance of the matchingnetwork 20C corresponding to a load of the power-stage amplifier 10Pdecreases, the P1 dB increases, and the linearity improves.

The gain (second gain) of the power-stage amplifier circuit 2P variesaccording to the impedance of the matching network 20C. In the caseillustrated in FIGS. 5A and 5B, as the impedance of the matching network20C decreases, the gain of the power-stage amplifier 10P decreases, andthe gain of the power-stage amplifier circuit 2P therefore decreases,too.

(2) Operation of RF Signal Processing Module 200

The control unit 3 detects a signal having information about a PAPR ofan RF signal generated by the RFIC 1, calculates the PAPR of the RFsignal, and then generates the second control signal S2 for reducing theimpedance of the matching network 20C as the calculated PAPR increases.As described above with reference to FIGS. 5A and 5B, as the impedanceof the matching network 20C decreases, the P1 dB of the power-stageamplifier 10P increases (the linearity improves), and the gain of thepower-stage amplifier circuit 2P decreases. Hence, as the PAPR of the RFsignal generated by the RFIC 1 increases, the P1 dB of the power-stageamplifier 10P increases (the linearity improves), and the gain of thepower-stage amplifier circuit 2P decreases in the case illustrated inFIGS. 5A and 5B. Incidentally, in the case where the P1 dB is increasedby reducing a load, in contrast with the case illustrated in FIGS. 5Aand 5B, the gain of the power-stage amplifier circuit 2P may increase insome cases.

As in the RF signal processing module 100, the control unit 3 generatesthe first control signal S1 for controlling the gain of the drive-stageamplifier circuit 2D so that a variation in the gain of the power-stageamplifier circuit 2P is compensated for.

The exemplary embodiments of the present disclosure have been describedabove. The power amplifier module 2 includes the first amplifier circuit2D configured to amplify an RF signal with a first gain corresponding toa first control signal S1 to generate a first amplified signal; and thesecond amplifier circuit 2P configured to amplify the first amplifiedsignal with a second gain corresponding to a second control signal S2 togenerate a second amplified signal. Hence, the first gain and the secondgain are individually controlled, thereby making it possible to flexiblycontrol the gain of the entire power amplifier module 2.

Furthermore, the second control signal S2 is a control signal forincreasing a power-supply voltage Vccp for the second amplifier circuit2P as a PAPR of the RF signal increases, and the first control signal S1is a control signal for controlling the first gain of the firstamplifier circuit 2D so that a variation in the second gain involved ina variation in the power-supply voltage Vccp for the second amplifiercircuit 2P is compensated for. Hence, the power amplifier module 2enables improvements in linearity and efficiency with a simpleconfiguration.

Furthermore, in the power amplifier module 2, the first control signalS1 may be a control signal Sd for controlling a power-supply voltageVccd for the first amplifier circuit 2D so that a variation in thesecond gain is compensated for. Hence, in the power amplifier module 2,the power-supply voltage Vccd for the first amplifier circuit 2D iscontrolled in accordance with a variation in the second gain, the firstgain thereby varies so that the variation in the second gain iscancelled out, and the entire gain thus becomes constant.

Furthermore, the power amplifier module 2 may include the variableattenuator 30 configured to attenuate the RF signal, and the firstcontrol signal S1 may be a control signal Sr for controlling a powerattenuation factor of the variable attenuator 30 so that a variation inthe second gain is compensated for. Hence, in the power amplifier module2, the amount of attenuation of a signal, which is to be inputted to thefirst amplifier circuit 2D, through the variable attenuator 30 iscontrolled in accordance with a variation in the second gain, the firstgain thereby varies so that the variation in the second gain iscancelled out, and the entire gain thus becomes constant.

Furthermore, the power amplifier module 2 may include the first matchingnetwork 20A configured to perform impedance matching between circuits,and the first control signal S1 may be a control signal Sa forcontrolling impedance of the first matching network 20A so that avariation in the second gain is compensated for. Hence, in the poweramplifier module 2, a reflected wave at the input end of the firstmatching network 20A is controlled in accordance with a variation in thesecond gain, the first gain thereby varies so that the variation in thesecond gain is cancelled out, and the entire gain thus becomes constant.

Furthermore, the power amplifier module 2 may include the secondmatching network 20B configured to perform impedance matching betweencircuits, and the first control signal S1 may be a control signal Sb forcontrolling impedance of the second matching network 20B so that avariation in the second gain is compensated for. Hence, in the poweramplifier module 2, the first gain of the first amplifier 10D varies sothat the variation in the second gain is cancelled out, and the entiregain thus becomes constant.

Furthermore, each of the RF signal processing modules 100 and 200includes the power amplifier module 2 including the first amplifiercircuit 2D configured to amplify an RF signal with a first gain togenerate a first amplified signal, and the second amplifier circuit 2Pconfigured to amplify the first amplified signal with a second gain togenerate a second amplified signal. Hence, in each of the RF signalprocessing modules 100 and 200, the first gain and the second gain areindividually controlled, thereby making it possible to flexibly controlthe gain of the entire power amplifier module 2.

Furthermore, each of the RF signal processing modules 100 and 200further includes the control unit 3 configured to generate a secondcontrol signal S2 for increasing a power-supply voltage Vccp for thesecond amplifier circuit 2P as a PAPR of the RF signal increases, and afirst control signal S1 for controlling the first gain of the firstamplifier circuit 2D so that a variation in the second gain involved ina variation in the power-supply voltage Vccp for the second amplifiercircuit 2P is compensated for. Hence, each of the RF signal processingmodules 100 and 200 makes it possible to achieve linearity andefficiency with a simple configuration.

The above-described embodiments are intended to facilitate understandingof the present disclosure, but are not intended for a limitedinterpretation of the present disclosure. The elements included in theembodiments, and the arrangements, materials, conditions, shapes, sizes,and the like of the elements are not limited to those exemplified in theembodiments, and can be appropriately changed. Furthermore,configurations described in different embodiments can be partiallyreplaced or combined with each other.

While preferred embodiments of the disclosure have been described above,it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the disclosure. The scope of the disclosure, therefore, isto be determined solely by the following claims.

What is claimed is:
 1. A power amplifier module comprising: a firstamplifier circuit configured to amplify a radio frequency signal with afirst gain and to generate a first amplified signal, wherein the firstgain corresponds to a first control signal; a second amplifier circuitconfigured to amplify the first amplified signal with a second gain andto generate a second amplified signal, wherein the second gaincorresponds to a second control signal; and a control circuit configuredto generate the first control signal and the second control signal,wherein the second control signal is configured to cause an adjustmentof a power-supply voltage of the second amplifier circuit as apeak-to-average power ratio of the radio frequency signal varies, andwherein the first control signal is configured to cause an adjustment ofthe first gain of the first amplifier circuit in a manner thatcompensates for a variation in the second gain resulting from avariation in the power-supply voltage of the second amplifier circuit.2. The power amplifier module according to claim 1, wherein the firstcontrol signal is configured to cause the adjustment of the first gainby causing an adjustment of a power-supply voltage for the firstamplifier circuit.
 3. The power amplifier module according to claim 1,wherein the first amplifier circuit comprises a variable attenuatorconfigured to attenuate the radio frequency signal, and wherein thefirst control signal is configured to adjust a power attenuation factorof the variable attenuator in a manner that compensates for thevariation in the second gain.
 4. The power amplifier module according toclaim 2, wherein the first amplifier circuit comprises a variableattenuator configured to attenuate the radio frequency signal, andwherein the first control signal is configured to adjust a powerattenuation factor of the variable attenuator in a manner thatcompensates for the variation in the second gain.
 5. The power amplifiermodule according to claim 1, wherein the first amplifier circuitcomprises a matching network configured to perform impedance matchingbetween circuits, and wherein the first control signal is configured tocause an adjustment in an impedance of the matching network in a mannerthat compensates for the variation in the second gain.
 6. The poweramplifier module according to claim 2, wherein the first amplifiercircuit comprises a matching network configured to perform impedancematching between circuits, and wherein the first control signal isconfigured to cause an adjustment in an impedance of the matchingnetwork in a manner that compensates for the variation in the secondgain.
 7. The power amplifier module according to claim 3, wherein thefirst amplifier circuit comprises a matching network configured toperform impedance matching between circuits, and wherein the firstcontrol signal is configured to cause an adjustment in an impedance ofthe matching network in a manner that compensates for the variation inthe second gain.
 8. A power amplifier module comprising: a firstamplifier circuit configured to amplify a radio frequency signal with afirst gain and to generate a first amplified signal, wherein the firstgain corresponds to a first control signal; a second amplifier circuit:comprising an amplifier configured to amplify the first amplified signalwith a second gain and to generate a second amplified signal, and anoutput matching network configured to perform impedance matching on thesecond amplified signal, wherein the second gain corresponds to a secondcontrol signal; and a control circuit configured to generate the firstcontrol signal and the second control signal, wherein the second controlsignal is configured to cause an adjustment of the second gain of thesecond amplifier circuit by causing an adjustment of an impedance of theoutput matching network.
 9. The power amplifier module according toclaim 8, wherein the second gain decreases as the impedance of theoutput matching network decreases.
 10. The power amplifier moduleaccording to claim 8, wherein the second control signal is configured tocause the adjustment of the impedance of the output matching network bycausing an adjustment of a variable reactance element of the outputmatching network.
 11. A power amplifier module comprising: a firstamplifier circuit configured to amplify a radio frequency signal with afirst gain and to generate a first amplified signal, wherein the firstgain corresponds to a first control signal; a second amplifier circuitconfigured to amplify the first amplified signal with a second gain andto generate a second amplified signal, wherein the second gaincorresponds to a second control signal; and a control circuit configuredto generate the first control signal and the second control signal,wherein the second control signal is configured to cause an increase ina power-supply voltage of the second amplifier circuit as apeak-to-average power ratio of the radio frequency signal increases. 12.The power amplifier module according to claim 11, wherein the secondamplifier circuit comprises an output matching network, and wherein thesecond gain decreases as an impedance of the output matching networkdecreases.
 13. The power amplifier module according to claim 11, whereinthe second amplifier circuit comprises an output matching network, andwherein the second control signal is configured to cause an adjustmentof an impedance of the output matching network by causing an adjustmentof a variable reactance element of the output matching network.